Gasoline operated pneumatic tool



July 17, 1951 H; c. DEARBORN 2,560,559

GASOLINE OPERATED PNEUMATIC TO0L 4 Sheets-Sheet 1 Filed Dec. 10, 1945July 17, 1951 H. c. DEARBORN 2,560,559

GASOLINE OPERATED PNEUMATIC TOOL Filed Dec. 10, 1945 4 Sheets-Sheet 2Henry 0. Dem-born July 17, 1951 H. c. DEARBORN 2,560,559

GASOLINE OPERATED PNEUMATIC TOOL Filed Dec. 10, 1945 4 ;Q'Sheet-s-Sheet5 gwue/wto'b Henry C. Dearborn July 17, 1951 H. c. DEARBORN 0,

GASOLINE OPERATED PNEUMATIC TOOL Filed Dec. 10, 1945 4 Sheets-Sheet 4awue/rvkw Henry 02 Dearbarn Patented July 17, 1951 UNI-"TED. sr s TENTOFFICE (Granted under the act of March 3,1883, as

' amended April 30, 1928; 370 Q. G. 757) 3 Claims.

This invention-pertains to improvements in a gasoline operated pneumatictool and especially to a, device designed as a hammer, vibrator, orpavement breaker. V

Ordinarily pneumatic tools are operated bycompressed air suplied by acompressor operated by a high horsepower engine.

An object of this invention is to provide a small, low-horsepowercombustion enginaicapable of supplying the necessary combustion fuelmixture to a combustion chamber in the pneumatic tool.

Another object of this invention is to provide a pneumatic tool which iscompact, light in weight, and is easily portable.

Details of the invention are described in connection with the followingdrawings'in which:

Fig. 1 is a diagrammatic showing of the assembly;

Fig. 2 is a longitudinal cross section of the engine;

Fig. 3 is asection pneumatic tool; i

Fig. 3a is an intermediate section of the pneu matic tool; and

Fig. 3b is the lower section oi the pneumatic tool.

"The device as shown consistsof a small two stroke cycl gasoline engine5!! which supplies compressed combustible fuel 'to -a combustion chamberin the pneumatic tool 53. Although the engine isshown as a separateunit, it would be practical to mount the small engine directly on thepneumatic tool to become an integralpart thereof.

Details of the engine design are shown in 2. Crankshaft It! has twothrows one of which is connected by means of connecting rod iii! topiston I98 in cylinder Hi3. Cylinder 198 is the power cylinder. Theother throw of crankshaft i0! is connected by means of connecting rodiii to piston H! in cylinder H53. Cylinder ill} is the compressioncylinder and compresses the combustion fuel for the combustion chamberof the pneumatic tool.

It will be observed that pistons use and H I travel towards each othersimultaneously and in so doing cause crankcase compression in thecrankcase. The gas so compressed has been drawn into the crankcasethrough the carburetor 40 and through poppet valve H6. When the pistonsreach the bottom of th stroke, piston I09 uncovers exhaust port Hi5, andthen uncovers intake port I22. This is conventional two stroke enginedesign. Piston H l uncovers intake port of the cylinder head in the 523only. On the return stroke a low pressure condition is set up in thecrankcase which then draws in a new charge of combustible fuel. PistonHill advances towards spark plug t2 and into firing position whilepiston H-l forces its compressed charge through valve lI.-2 intomanifold Crankshaft 16! carries flywheel 62 which is provided withgroove H33 adapted to "receive a rope starter. Flywheel M22 providedwith fan blades 84 and W3 on itscircumference. These blades provide acooling flow-of air over the oylinders. Mounted on the underside of theflywheel are permanent magnets :1 BE and lil i which are carried pastfield coils l fl l to provide low tension current for a purpose laterdescribed.

Compressed fuel in'engine manifold E E5 is conducted through hose 3-5 toa manifold M on the pneumatic tool. Passage of this-gas is controlled bypoppet valve .31! which can be opened or closed by the operator .uponmoving grip lever 52, inasmuch as lever 92 is connected by link 38 andlever 32 to operate valve 38. Upon opening of valve 3d, gas, underpressure passes into the cylinder head manifold of the pneumatic .tooland, being under pressure, opens valve M. Valve M3 is normally held inclosed position by lever 22 which is lifted by spring 28.

Compressed fuel is thus conducted to combusti'on chamber 34. Piston ichamber 3 3 is held against compression by means of long coil spring I.

Passageway 29 in the tool cylinder head con-j ducts the gas to adiaphragm switch It. When a predetermined pressure is reached diaphragmi5 is distorted to provide an electrical connection across posts It and11. Electrical energy supplied by the engine magneto is fed through athree cable conduit 9 through line D to energize magnets 2!. Thisresults in a lifting action on lever 22 to cause valve M to seat. Thesame connection causes a flow of current through wire A to energize arelay which makes a circuit with a high tension coil thereby producing aspark producing current which is conducted by high tension line l9 tospark plug 23. The spark thus produced ignites the charge in combustionchamber 34 causing piston l to strike anvil 26.

Relatively low pressure. in this manifold will cause valve i l to open.

below combustion.

'3 The force of the blow on the anvil is transmitted to tool bit 25.This bit is removable and interchangeable to permit the use of varioustypes of tools and is retained by retainer spring 24.

Piston I at the bottom of its stroke uncovers ports 21A and 213 incylinder 2. These ports permit the escape of burned fuel. Pressure beingthus relieved in the combustion chamber results in automatic opening ofvalve M to permit an inflow of fresh gas which is compressed by thereturning piston propelled by spring 1.

As previously stated, escaping gas after combustion is ejected throughports 21A and 27B and in flowing through these ports is conductedthrough openings in the handle support assemblies 28 and 29. The flow ofexhaust gas through ports 21A and 2113 will set up a flow of air, whichwill cool the fins on cylinder 2.

Since it is standard practice to mix lubricating oil with the fuel in atwo stroke cycle engine, adequate lubrication will be provided by thefuel.

The engine is built as small as practical for the obvious purpose ofobtaining maximum weight reduction. The speed of the engine must beadequate to provide the desired fiow of combustible mixture. Thus, ifthe engine has only one third the displacement of the hammer it would be'necessary to run the engine at 3000 R. P. M.s to provide 1000 hammerblows per minute.

It will be apparent that the assembly may be modified by substituting afour stroke cycle engine to pump the combustible fuel or there may be aunit to pump only air with means provided to inject fuel. may be of anydesired conventional design.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor.

Having described my invention, I claim:

1. In a pneumatic tool providing a tool bit, the combination of a headfor said tool bit, a combustion chamber, a piston engageable with saidhead reciprocable in said chamber, an exhaust port uncovered by saidpiston at one end of its stroke, a spring for returning said piston tooperative position, a manifold connected to said chamber by a port, asolenoid operated valve located in said port, ignition means in saidchamber, a switch responsive to pressure in said chamber forsimultaneous operation of said solenoid and said ignition means by anelectrical current, a second port opening into said manifold, and aseparate compressor for fuel connected to said second port by flexibleconduit, said compressor comprising one cylinder of a two cylinder twocycle internal combustion engine having one carburetor for supplyingfuel to the cylinder used as a compressor and to the other or drivingcylinder and having a by-pass conduit connecting said flexible conduitwith said crankcase with a pressure responsive valve in said by-pass,where- The body of the pneumatic tool by said compressor supplies thetool with a fuelair mixture at a constant pressure.

2. A tool comprising a combustion chamber, a piston slidable in saidcombustion chamber adapted to impart striking force to a tool bit, valvemeans opening into said combustion chamber for admitting a fuel charge,an exhaust port opening into said combustion chamber, a constantpressure compressor consisting of two cylinders mounted on and openinginto a crankcase, a piston in each cylinder operative together on onecrankshaft in said crankcase, a carburetor adapted to admit a fuelcharge to said crankcase, passages connecting said crankcase with a portin the lower end of each of said cylinders for the conduction of fuelcharges thereto, said ports being uncoverable by said pistons at theirdown-stroke position, a conduit connecting the first of said cylinderswith said valve means on said combustion chamber, a pressure reliefvalve connecting said conduit with said crankcase, a second exhaust porton the second of said cylinders, and ignition means for the second ofsaid cylinders and said combustion chamber.

3. A constant pressure compressor for supplying a fuel-air mixture to aportable explosively operated tool at a constant pressure comprising twocylinders mounted on and opening into a crankcase, a piston in eachcylinder operative to gether on one crankshaft in said crankcase, acarburetor adapted to admit a fuel charge to said crankcase, passagesconnecting said crankcase with a port in the lower end of each of saidcylinders for the conduction of fuel charges thereto, said ports beinguncoverable by said pistons at their down-stroke position, a flexibleconduit connecting the first of said cylinders with the inlet of thetool, a by-pass connecting said crankcase with said conduit, a pressureresponsive valve in said by-pass, an exhaust port on the second of saidcylinders, and ignition means for the second of said cylinders.

HENRY C. DEARBORN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 865,889 Harford Sept. 10, 1907890,546 Wittmann June 9, 1908 1,008,863 Reuter Nov. 14, 1911 1,033,503White 'July 23, 1912 1,088,761 Anderson Mar. 3, 1914 1,598,476 CribierAug. 31, 1926 1,934,935 Luxmore Nov. 14, 1933 2,394,904 Fowler Feb. 12,1946 2,402,920 Seibold June 25, 1946 2,403,398 Reggio July 2, 1946FOREIGN PATENTS Number Country Date 255,519 Great Britain July 21, 1926

